Johnson 80hp sneezing when I throttle up

[BonairII]

I'm ready to pull my hair out right now, so I'm taking a break. Hopefully someone here can help me think this darn sneeze issue out.

-new plug wires, plugs(gapped .030), new coil wire
-new fuel lines and connectors
-new t-stat
-rebuilt fuel pump today
-drop tested cylinders....all are firing

I've been chasing down air leaks for the last few days. I put a clear hose from the fuel pump to carb and eventually stopped the air from getting into the system. The clear line is still attached to the system until I get everything worked out.

Today, I rebuilt the fuel pump and then had an issue of sediment bowl not filling fast enough as the motor idled. I could press the fuel bulb and fill the clear sediment bowl, but the fuel pump wasn't filling it on it's own. Took it apart a couple times and reassembled and then tightened all clamps again. Seems to be staying full now.

Motor is idling fairly well now, but when I throttled up(as far as the motor will let me while it's in neutral), I starts to sneeze(see video).

http://www.youtube.com/watch?v=m2I7RfS6Oc0

Carb has been cleaned this week. I replaced the base gasket and set the float (parallel with carb body). Needle and seat are clean and in great shape. All orifices cleaned with small wire and carb spray. I pulled the fixed high speed jets a few minutes ago just to be sure nothing clogged them. They were/are clean.

Motor was link and synced again.

What am I missing? Could the float level be wrong and slightly starving the motor of fuel when I throttle up?

This is so darn frustrating.

 

[boobie]

Re: Johnson 80hp sneezing when I throttle up

The last time I heard that on that mtr I opened up the low speed adjustments on the carb. If not your sync & link is off. Or you still have some junk in your carb or a bad cyl. What's your compression ??

 

[BonairII]

Re: Johnson 80hp sneezing when I throttle up

I think the low speed needles are already 1 3/4 turns out, but I guess I can turn them out a bit more.

If indeed my link and sync is wrong (I used service manual), what is possibly off? Butterflies not opening up enough as dist advances timing?

I did the link-n-sync in the fall and motor was running well....so I must have done it correctly. But I put the original carb back on the motor recently cause the other carb had some problems with the choke lever hardware, etc. Maybe I changed something by accident.

 

[nwcove]

Re: Johnson 80hp sneezing when I throttle up

if the motor was working good, and you changed the carb, and now it has the "miss", id try putting the other carb back on.

 

[BonairII]

Re: Johnson 80hp sneezing when I throttle up

I opened the low speed needles to 2 full turns out and sneeze seems to be gone(or very close), but i only ran it for short time. Gonna have to do a bit more testing after dinner.

 

[boobie]

Re: Johnson 80hp sneezing when I throttle up

Try a little more out til it wants to slow down and then back in a little.

 

[BonairII]

Re: Johnson 80hp sneezing when I throttle up

My service manual says to start at only 3/4 turn. Why do I need to be at 2 full turns out to get it to run correctly? Cause motor is old now?

 

[boobie]

Re: Johnson 80hp sneezing when I throttle up

Could be, because the pistons and rings don't have as much "suck" on the up stroke as they used to. Did you ever do a good decarb on it??

 

[BonairII]

Re: Johnson 80hp sneezing when I throttle up

Yup. I ran 3 full gallons of the decarb mix (can of seafoam/gallon of premix) through it. The smoking never did stop though. I ran WOT for awhile on the water after the decarbs.

This is what it looked like as I was running the 3rd gallon(but before the WOT runs on the water).

http://www.youtube.com/watch?v=sgbHO8hzGgA

Compression stayed the same (90psi)on all 4 holes.

 

[boobie]

Re: Johnson 80hp sneezing when I throttle up

Did you ever have the core plugs out of the carb to see if there was any crap behind them ??

 

[BonairII]

Re: Johnson 80hp sneezing when I throttle up

Did you ever have the core plugs out of the carb to see if there was any crap behind them ??

Nope, never took out core plugs.

I splashed the boat today...was almost 70 degrees here in NY. Got to the launch and realized that the floating docks weren't in the water yet. :facepalm:

Had to wade in up to my knees in very COLD water to get the boat shoved off.

Motor started up very well and idled well. I ran it around for about 30 minutes. It got out of the hole pretty well, but only got up to 30mph(got to 33mph in Sept). I trimmed the motor up one notch to the '3rd hole'(manual tilt/trim) and got 31mph.

Gonna fiddle with the link-n-sync on Thurs when I launch it again, to see if I can make the throttle response a tad snappier.

I've got to figure out how to tighten out the swivel mount on the motor cause it's turns WAY to easily now that it's all greased up well.

 

[BonairII]

Re: Johnson 80hp sneezing when I throttle up

Going to take the boat out again tomorrow or Sunday to do some more testing/tweaking, but before I do I've got a fuel pump and fuel line diameter question....

After replacing all of the 1/4" ID fuel line with 5/16ths line(including all hose on the motor itself), I've started to second guess myself on the larger diameter hose. (someone mentioned to me that that the larger hose 'possibly' could cause problems)

I just rebuilt my fuel pump, but could the 25% larger ID hose lower the fuel pressure enough to affect performance? If so, would there be any definitive symptoms?

I hate to keep over thinking all of this, but until I know for sure...it'll always be in the back of mind.

 

[boobie]

Re: Johnson 80hp sneezing when I throttle up

The 5/16 " fuel line should give you no probs as long as all the connections are tight and clamped properly.

 

[BonairII]

Re: Johnson 80hp sneezing when I throttle up

Ok. Good. Now I won't worry about it anymore.